old age

Is it normal for a old dalmatian dog to lose control of bowel movements at night, and poop in his bed?  For the last two months he has been pooping in his bed at night, which is totally not in his character.  It seems to be from old age, and he can't control it.  We go for many walks a day, even more than my dal wants.  He walks super slow, so I have to be very patient with him.  
Any suggestions?

[Aleda M Cheng, D.V.M., C.V.A]

Unfortunately, it can be a consequence of aging.   The innervation of the rectum can be slowed down or interrupted by spinal arthritis or degenerative myelopathy or other age related disorders.